I am wondering about, for example, DNA. Is it safe to say that if you leave a long DNA molecule alone to weather the forces of nature, then we may point to entropy as the central culprit in its eventual break down into nucleotides, molecules, atoms, etc?

If so, then a functional DNA molecule can be said to be in a more ordered, lower entropy state then one broken into its constituent parts.

And if the universe started off with low entropy, tends towards an increase in entropy, and DNA obviously didn't exist until billions of years later, then is it that the universe on average increases in entropy that explains away that somewhere/time locally the direction of entropy actually reversed in the formation of a DNA molecule?

There are many ways to state the 2nd Law of Thermodynamics, but all of them, in one way or another, apply only to a hypothetical closed system. Novices tend to overlook that restriction, or they assume a system is closed when, in fact, it is exchanging matter, energy or information with something outside of the perceived system.

It is widely assumed that the universe is a closed system, but this too is a fallacy. The expansion of space is an input from outside of what we perceive as our universe. This input of new space is a heat sink, which throws a giant monkey wrench into our understanding of increasing entropy.

If the universe is infinite, then any finite part of it may be exchanging matter, energy or information with the rest of it. So even without expansion, the question of whether an infinite universe is an open or closed system is indeterminate.

Galaxies, solar systems and planets are open systems. The most obvious of these is our planet, which receives low-entropy solar radiation with a color temperature around 5000 K and emits high-entropy heat radiation at around 290 K. This flow of entropy results in accumulation of complexity on the planet's surface, which takes the form of life.

Each organism is also an open system. For a time, an animal consumes low-entropy nourishment and exports high-entropy feces. The result is growth and reproduction. Later, the entropy flow reverses the organism dies, and other organisms consume its low entropy nourishment.

I like to think of entropy as a sort of Universal Tax. The only way to escape it is to do absolutely nothing!

The creation of the DNA resulted in a more ordered state of the DNA, but I would think that was at the expense of a greater amount of expended energy, so the total entropy of the Universe increased.

If I have it right, entropy can be reduced locally, but it always increases Universally. The energy in our Universe is never destroyed, but entropy tends to even that energy out so that it cannot do anything useful.

Oh, no, not infinity, that’s going to let Bill S. into the thread!!!!!!

If the observable Universe started with the Big Bang, that, as Roger Penrose stresses, (quick spot of name dropping, there) must have been a very special, low entropy condition. However, once we introduce the idea of the infinite we have to accept that the Big Bang could not have been the start of everything. Something must always have existed. For convenience let’s call that something the cosmos. We now have to ask questions like: Does the 2nd law apply to the cosmos? On the face of it, it might seem reasonable to suggest that it does, but if the cosmos is infinite then entropy must have “maxed out” infinitely long ago. In this case the 2nd law and the increase of entropy must be local phenomena, and may be no more than illusions that are necessary to allow us to make sense of our 4D Universe.

If antimatter is ordinary matter going backwards in time then it exerts negative gravity upon ordinary matter. In which case a black hole recycles matter into antimatter (or vice verse) thereby reversing entropy.

And yes, I know this is not a mainstream idea but there is nothing to the best of my knowledge in physics that precludes it. Personally, I believe this is how the Universe works. One or multiple black holes at the end of one universe cycle become white holes at the start of the next. The arrow of time reverses thereby reversing entropy.

So, the above is not an infinite universe but rather an infinite series of finite universe cycles. Each full cycle consists of a matter universe followed by an antimatter universe. At the end of each full cycle the total time that they have existed as a pair is zero.

The beauty of this version of a cyclic universe is that by reversing the arrow of time, entropy is reversed and at the start of each universe cycle the universe starts with a full complement of elementary particles, namely hydrogen and helium atoms, the fuel the universe relies upon to create everything else.

If the observable Universe started with the Big Bang, that, as Roger Penrose stresses, (quick spot of name dropping, there) must have been a very special, low entropy condition. However, once we introduce the idea of the infinite we have to accept that the Big Bang could not have been the start of everything. Something must always have existed. For convenience lets call that something the cosmos. We now have to ask questions like: Does the 2nd law apply to the cosmos? On the face of it, it might seem reasonable to suggest that it does, but if the cosmos is infinite then entropy must have maxed out infinitely long ago. In this case the 2nd law and the increase of entropy must be local phenomena, and may be no more than illusions that are necessary to allow us to make sense of our 4D Universe.

You can only invoke the Cosmos if you are talking about Penfold rather than Penrose.

The 2nd law may not apply to the Cosmos, but it does apply to this Universe. Beyond that, science is no help at all because all bets are off.

If antimatter is ordinary matter going backwards in time then it exerts negative gravity upon ordinary matter. In which case a black hole recycles matter into antimatter (or vice verse) thereby reversing entropy.

And yes, I know this is not a mainstream idea but there is nothing to the best of my knowledge in physics that precludes it. Personally, I believe this is how the Universe works. One or multiple black holes at the end of one universe cycle become white holes at the start of the next. The arrow of time reverses thereby reversing entropy.

So, the above is not an infinite universe but rather an infinite series of finite universe cycles. Each full cycle consists of a matter universe followed by an antimatter universe. At the end of each full cycle the total time that they have existed as a pair is zero.

The beauty of this version of a cyclic universe is that by reversing the arrow of time, entropy is reversed and at the start of each universe cycle the universe starts with a full complement of elementary particles, namely hydrogen and helium atoms, the fuel the universe relies upon to create everything else.

Again I must stress this is not a mainstream idea.

Gee, Mike, why does all that sound so familiar? Oh, yea! You're putting your own spin on stuff that I wrote concerning my own model. Uh oh! Now I'm gonna get my knuckles wrapped for mentioning my model.

Censored posts still may be viewed by viewing the poster's profile and clicking on "Show Posts". In this case, I have to agree with the moderator. Those two posts were advancing new theory in the mainstream forum.

First off, as for the above few posts, I unwittingly noticed that censored posts show up when you click reply if anyone wants to see them.

Now, since there's (of course) no real consensus on whether or not the universe is infinite, I'll make an educated guess here that it is finite for the purposes of this topic and discussion. So let's assume that the universe is finite, and thus a closed system, allowing for a traditional application of the 2nd law.

I don't mean to seem repetitive, but I would love to hear your thoughts to this: is the local decrease in entropy in the formation of the first DNA molecule only explained by an average increase in entropy? Or are there other explanations that might potentially explain this decrease?

And if the average increase of entropy is the only scientific explanation (though you might find it completely sufficient), do any of you find it at all significant to note that, even if as Geezer suggests that the formation of DNA overall increases entropy and the numbers add up, it is never-the-less plain to see that at the moment and place a DNA molecule was spontaneously formed, entropy spontaneously decreased to allow it? Is that not significant?

Some of you, I'm sure, are probably thinking that I'm about to turn this topic into a forum to push a religious message. Don't worry, while my intentions here are based in "religion", they are also entirely personal. [Edit: Please] Just enjoy the discussion on entropy.

Hi PhracWhat I wrote in the previous post was based on a theory I wrote about twenty years ago (which I can prove if need be). I mentioned it in my post as I believe it is very relevant to entropy. If correct, it is the only mechanism whereby entropy can be reversed.

ClipI don't mean to seem repetitive, but I would love to hear your thoughts to this: is the local decrease in entropy in the formation of the first DNA molecule only explained by an average increase in entropy? Or are there other explanations that might potentially explain this decrease?

And if the average increase of entropy is the only scientific explanation (though you might find it completely sufficient), do any of you find it at all significant to note that, even if as Geezer suggests that the formation of DNA overall increases entropy and the numbers add up, it is never-the-less plain to see that at the moment and place a DNA molecule was spontaneously formed, entropy spontaneously decreased to allow it? Is that not significant?

I don't think it is significant. DNA was created by pure chance. The energy used to create it contributed to the overall increase in entropy. Life does not decrease entropy as it consumes food (energy). Overall in any closed system entropy always increases.

Hi PhracWhat I wrote in the previous post was based on a theory I wrote about twenty years ago (which I can prove if need be). I mentioned it in my post as I believe it is very relevant to entropy. If correct, it is the only mechanism whereby entropy can be reversed.

I would be very interested to see how you arrived at so many points of agreement with what I deduced from my own model. PM me a link or discuss it in New Theories. If we independently arrived at the same set of conclusion, there must be some truth in them.

There is a difference between randomness and chaos. Given sufficient time and a sufficient mix of the right chemical elements, random events will eventually assemble a simple DNA molecule. Whether that molecule will replicate and combine with others depends on the flow of entropy. Each combination of DNA base pairs is a strange attractor; some attractors have half-lives in picoseconds, others may last indefinitely in a favorable environment. Too much entropy in the environment will shorten the life expectancy of DNA molecules. They cannot combine to produce higher life forms without exporting entropy. To have a place to send that entropy, it must be an open system. Organisms export entropy as poop; the entropy of the poop eventually ends up as heat which is exported in the black body radiation of the planet into the cold expanse of space. I think that is a sufficiently scientific explanation to avoid being labeled "religion". However, there are religions which hold that, "God doesn't play with dice", as Einstein put it. Personally, I think God IS dice. I think the universe is based on chaos; there is no divine plan.

Can I point out that there is a common problem with thinking about entropy as "randomness" because this is only true for particles that do not interact in any way at any temperature and this is the easiest way to demonstrate the basic meaning of the concept.

This is not true if the particles interact with each other

One way of illustrating this is to take a simple gas say hydrogen and cool it down i.e. slow down the molecules. eventually the molecules will start to stick together and it will condense into a liquid and finally a solid crystalline material with considerable order in its structure. After that if left undisturbed it will stay that way indefinitely and not become disordered.

So to quote discworld. If our universe was destined to turn into turtles. It would be turtles all the way down :-)

All particles in our universe interact in some way even if it is only by gravity. In fact gravity defines the eventual demise of our universe which is for all the material to collapse onto black holes and then have the black holes slowly radiate away over vast orders of magnitude of time greater than the collapse took. This produces very low frequency electromagnetic radiation which essentially does not interact with itself leaving a tiny amount of higher frequency em radiation and a few particles behind in the last few million years of its existence.

Large black holes are extremely cold and lose their energy extremely slowly getting hotter as they lose their mass. a normal black hole with 5 solar masses is a few miles across and is far cooler than the microwave background radiation at 10^-8 of a degree K it therefore emits thermal electromagnetic radiation at a peak frequency of about one cycle per second and lasts 10^60 billion years before it evaporates. This is about as small a black hole our universe can make at the moment.

For a black hole to be about the same temperature as the sun 6000 degrees k it has to be down to the mass of a smallish asteroid and a bit bigger than an atom in size and would radiate energy at about one microwatt and last 10^25 billion years before it finally evaporated.

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